The two issues, though relatively minor in the broad sweep of decades of bilateral hostilities, underlined both the opportunities and limits for improved relations facing the new governments of Barack Obama and Raúl Castro.

Havana's decision to allow the prison visits "reflect the benefits that could accrue to both countries as a result of better communications and, conversely, how our interests are poorly served when we don't communicate," said Bob Pastor, the top Cuban expert in Jimmy Carter's administration.

The State Department confirmed Wednesday that acting Deputy Assistant Secretary of State Bisa Williams visited with jailed dual U.S.-Cuban citizens there during her trip to Cuba last month to discuss a possible resumption of direct mail services between the two nations. No further details on the visits were available.

Like other countries, including the United States, Cuba does not recognize dual nationalities. Cuba treats those cases as Cuban-only citizens and regularly denies foreign consular officials on the island access to the dual citizens jailed there.

State Department officials are known to have long been pressing for U.S. consular access to the U.S.-Cuban citizens jailed in Cuba. "We hope the U.S. consular access to dual nationals imprisoned in Cuba would be on a continuing basis," the department said.

Cuba has imprisoned 19 U.S. citizens, including 10 or 11 believed to also have Cuban citizenship, according to the State Department. Those who have only U.S. nationality already receive consular visits. The charges against both groups include migrant smuggling, drug trafficking or possession, homicide and corruption of minors.